Conspiracy theories are nothing new. As Tim Mendham from the pro-science Australian Skeptics group told news.com.au, some 130 years ago there was a popular theory that a cabal of Zionists controlled the world.

But now, because of electronic mass media, the rumours spread faster than ever.

News.com.au has taken a look at some of the new theories that have caught on - as well as a few old ones that have come alive again.

Most of them have one thing in common As Mr Mendham explains, many theories are perpetrated because of an aggressive mistrust of people and things - particularly of the Government or institutions many of us tend to give the benefit of the doubt.

"Most people actually have trust..." Mr Mendham said. When your friends make mistakes or do something stupid, you still tend to trust them. "You give them leeway."

1. LORDE ISN'T 17

'No way Lorde is 16 or 17 or whatever though': a tweet from a Lorde truther...Source:NewsComAu

The report said: WTC 7 was unlike the WTC towers in many respects. WTC 7 was a more typical tall building in the design of its structural system. It was not struck by an aircraft.

The collapse of WTC 7 was caused by a single initiating event - the failure of a northeast building column brought on by fire-induced damage to the adjacent flooring system and connections - which stands in contrast to the WTC 1 and WTC 2 failures, which were brought on by multiple factors, including structural damage caused by the aircraft impact, extensive dislodgement of the sprayed fire-resistive materials or fireproofing in the impacted region, and a weakening of the steel structures created by the fires.

Despite that, it's unlikely this idea - about one of the defining events of our age - will ever die.

That's the thing with conspiracy theories. "They're very hard to kill off," said Mendham. But if you make an extraordinary claim, he added, you should have some pretty big facts to back you up.

* Also defined by a likely truther on the same website as "One who is not blind and ignorant".